Before running each test, Django resets the database to its initial state, as it would be after running migrations. Most tests will need the creation of some initial objects to set the state. Rather than creating different initial objects for different scenarios, a common set of initial objects are usually created.
This can quickly get unmanageable in a large test suite. The sheer variety of such initial objects can be hard to read and later understand. This leads to hard-to-find bugs in the test data itself.
Being such a common problem, there are several means to reduce the clutter and write clearer test cases.
